BORON

BORON GROUP

Atomic number:

5

Group numbers:

13

Period:

2

Electronic configuration:

[He] 2s2 2p1

Formal oxidation number:

+3

Electronegativities:

2.04

Atomic radius / pm:

79.5

Relative atomic mass:

10.811 ± 0.007

Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy (GB) and independently by Joseph-Louis Gay-Lussac and Louis-Jaques Thénard (FR). The origin of the name comes from the Arabic word buraq and the Persian word burah meaning boraks (Na2B4O7*10H2O). It is hard, brittle, lustrous black semimetal. Boron is unreactive with oxygen, water, alkalis or acids. It combines with most metals to form borides. Boron is obtained from kernite, a kind of borax (Na2B4O7*10H2O). High purity boron is produced by electrolysis of molten potassium fluroborate and potassium chloride (KCl). Amorphous boron is used in pyrotechnic flares to provide a distinctive green colour and in rockets as an igniter.